Remove Babel (#1074)

* Test helpers no longer rely on Babel.

* Behaviours are no longer imported.

* Removed Babel dependency.

* Fixed linter errors.

test/token/ERC20/TokenTimelock.test.js

@@ -1,5 +1,5 @@
-import latestTime from '../../helpers/latestTime';
-import { increaseTimeTo, duration } from '../../helpers/increaseTime';
+const { latestTime } = require('../../helpers/latestTime');
+const { increaseTimeTo, duration } = require('../../helpers/increaseTime');
 
 const BigNumber = web3.BigNumber;